I just finished making a comment to @Elemtilas' answer and feel that it makes sense to embed it into an answer.
United States Supreme Court Justice Potter Stewart in the famous 1964 case Jacobellis v. Ohio said...
I shall not today attempt further to define the kinds of material I understand to be embraced within that shorthand description ["hard-core pornography"], and perhaps I could never succeed in intelligibly doing so. But I know it when I see it.
That's half the problem we're facing here, and I'll get to that momentarily. In commentary to and criticism of Justice Stewart's famous statement, William T. Goldberg said...
This simple phrase, embedded in a plurality opinion, carries with it many of the conflicts and inconsistencies that continue to plague American obscenity law. In effect, "I know it when I see it" can still be paraphrased and unpacked as: "I know it when I see it, and someone else will know it when they see it, but what they see and what they know may or may not be what I see and what I know, and that's okay."
And that's the other half of the problem.
Is it OK? Who's an expert?
Questions and answers in this Meta have famously asked the question, "who's an expert on magic?" Nobody, obviously, since (insofar as we can prove) magic doesn't exist. But that's an inaccurate perspective because when it comes to this and only this website, the real question is, "who's an expert in constructing magic systems?" Such people are experts and, since the OP isn't, they can judge whether or not there's enough detail.
But that's only half the problem...
- Because there's a lot of us who have enough experience to be really, really dangerous and so we think we're experts.
- And then there's those people who think all things worldbuilding should be strictly and rigidly based in science falsely so called, meaning that they erroneously believe that what facts (science) we understand today represent truth. It doesn't, but that's an issue for another post. The point here is that these, the scientists falsely so called, demand a different set of details than the experts and the experts falsely so called. (Laugh with me people!)
- And then there's those people who judge the question based on their level of education and expect yet another set of details.
- And then there's those people who speak English as a second language, which means the question may be difficult to understand or the respondent may not have a good enough grasp of colloquial English to understand the question — and so here's another set of details....
I can go on, but I hope you see the point. Ours is not a Stack that depends on the predictable objectivity of, for example, programming. Ours is ridiculously, gloriously, even blessedly imaginative.
And that's the problem.
Having just made a similar comment to a Sandbox post I believe myself oddly prepared to make the following statements. I could be wrong, but this is my story and I'm sticking to it.
- The OP must be ridiculously clear, complete, and focused with the actual question. They cannot ever, ever, ever assume that anyone knows what they're talking about — because they're yet another of those people assuming what level of detail is needed and we will jump to conclusions since we can't read the OP's mind and don't know anything about the OP personally. How one asks a question on this site is a bigger deal than on any other Stack. (IMHO)
- The OP must tell us what details specifically matter, and what details specifically don't. If the justification for why something matters or not is important to the question, then include it. If not, DON'T INCLUDE IT, just tell us bluntly, "why this is the way it is, is irrelevant to the question and may not be considered for answers." Why do I love conditions like that? Because if a respondent passionately believes that you have no honking idea what you're talking about, it forces them to answer with a (hopefully) well-thought-out Frame Challenge rather than some comment telling the OP there are too many/few details.
- The backstory (which really is different from the details) is interesting, but functionally irrelevant. Including it is almost always a bad idea unless the OP is very clear about it being nothing more than entertainment. An OP can really confuse respondents by interweaving the backstory with the question and its conditions — putting people in the position of judging the backstory. When an OP is thinking about "details," they must think carefully about what really is a FACT or CONDITION that's needed to understand the question and what's just cool story. This is perhaps the most challenging and most frustrating aspect about asking questions here. We're doing it (usually) because we're writing a story or building a game and we think (think!) that the story or game is important to the question. It isn't. Or, more accurately, if it is, it's not a worldbuilding question.
As you might imagine, the Sandbox is your friend.
Conclusion
How much wood can a woodchuck chuck if a woodchuck could chuck wood?
He would chuck all the wood that a woodchuck could chuck if a woodchuck could chuck wood.
There is no objective answer to your question. You need the right amount of detail to make the majority of respondents happy. If people point out the need for additional detail, you need to edit the post (not make a comment...) to include it or explain why it should be ignored. You need to be patient because you're dealing with everybody from inexperienced teenagers to experienced old folks and everyone from moderately educated junior high school students to sometimes over educated professionals and PhDs. We're going to have a disastrously diverse set of opinions about what the right amount of detail should be.
But in the end, it's really YOU who makes that decision. This is a blunt and ruthless observation, but if a question was closed because there was too much detail, it was you who failed to remove extraneous errata or explain why it was needed. If it was closed for too little detail, it was you who failed to either provide additional detail or explain why it isn't needed. Because the public has a funny way of deciding for itself what's "right."
Welcome to democracy my friend. And as Sir Winston Churchill once said...
Many forms of Government have been tried, and will be tried in this world of sin and woe. No one pretends that democracy is perfect or all-wise. Indeed it has been said that democracy is the worst form of Government except for all those other forms that have been tried from time to time.…